Noncontact tonometer

ABSTRACT

A tonometer for quickly and efficiently remeasuring intraocular pressure when an intraocular pressure is higher or lower than a predetermined pressure. It is determined whether a predetermined number n of intraocular-pressure measurements have been completed, wherein when n intraocular pressures exist, the n intraocular pressures are compared with a predetermined upper limit and lower limit. When the n intraocular pressures are between the upper limit and the lower limit, it is then determined whether the measurements of left and right eyes have been completed. When the measurements have not been completed, a measuring section is moved to the other eye. When the lateral movement has been completed, the next intraocular-pressure measurement is performed. When, among the n intraocular pressures, at least one intraocular pressure outside the predetermined upper and lower limits exists, a warning is given.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a noncontact tonometer for measuringintraocular pressure by blowing fluid such as air against the cornea ofa subject eye to deform it and detecting and analyzing a change in indexlight projected onto the cornea.

2. Description of the Related Art

Noncontact tonometers have the advantages of no eye contact andrequiring no eye-drop anesthetic and so on, thus being broadly used inthe field of ophthalmology for screening to detect glaucoma caused byhigh intraocular pressure. When intraocular pressure is more than apredetermined value, close examinations including an eyegroundexamination and campimetry are performed.

An automatic positioning system is disclosed in Japanese PatentLaid-Open No. 9-84760 assigned to the same assignee as this application,in which an index image projected on a subject eye is sensed todetermine the relative position between the eye and a measuring section,and a stage is controlled by motor drive.

Also, noncontact tonometers capable of full automatic measurement aregoing into practical use in which upon completion of predetermined timesof measurements, the measuring section moves automatically to the othereye that has not yet been measured to position it and makes apredetermined number of measurements.

With the related-art noncontact tonometers, however, if eyelashes arecaught on the cornea during the measurement, the resistance of theeyelashes prevents the cornea from being sufficiently deformed, so thateven when the actual intraocular pressure is within a normal range, thereading sometimes indicates a higher value. Also when the fixation ofthe subject eye is out of place, the reading shows a lower value thanthe actual intraocular pressure, but only rarely. Therefore, when theintraocular pressure is higher or lower than a predetermined value,examiners perform remeasurement for confirmation.

In a case with a fully automatic system in which a measuring position issensed, positioned automatically, and a predetermined number ofmeasurements are sequentially performed for both eyes, when apredetermined number of measurements for one eye have been completed,the measuring section is moved to the other eye that has not yet beenmeasured and performs a predetermined number of measurements. Therefore,the measuring section must be moved again if remeasurement for the firstsubject eye is necessary, thus preventing the reduction in the timerequired for measurements. Also, since the measuring operation has beencompleted, the measurement for confirmation is sometimes forgotten.

SUMMARY OF THE INVENTION

The present invention can provide a noncontact tonometer capable ofsolving the above-described problems to quickly and efficiently performremeasurement for confirmation when intraocular pressure is higher orlower than a predetermined value.

The present invention proposes a noncontact tonometer characterized inthat a predetermined intraocular pressure and a measured intraocularpressure are compared in magnitude and a measuring operation is varieddepending on the comparison.

Further objects, features and advantages of the present invention willbecome apparent from the following description of the preferredembodiments (with reference to the attached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a first embodiment of the presentinvention.

FIG. 2 is a perspective view of a prism diaphragm.

FIG. 3 is a flowchart for the control operation of the first embodiment.

FIG. 4 is an explanatory diagram of a setting screen of a monitor.

FIG. 5 is an explanatory diagram of an intraocular pressure and amessage on the monitor.

FIG. 6 is a flowchart for the control operation of a second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be specifically described with reference tothe illustrated embodiments.

First Embodiment

FIG. 1 shows the arrangement of a measuring section of a noncontacttonometer; objective lenses 10 and 11 are disposed on an optical axisL1, facing a subject eye E, and a nozzle 12 is disposed on the centralaxis thereof. A fluid chamber 13, an observing window 14, dichroicmirrors 15 and 16, a prism diaphragm 17, an imaging lens 18, and animage-pickup element 19 are arranged in line on the back of the nozzle12.

The elements including the objective lens 10 through the image-pickupelement 19 make up an observation system and an alignment check systemfor the subject eye E. External eye-illuminating light sources 20 a and20 b are disposed in the positions symmetrical with respect to theoptical axis of the objective lenses 10 and 11, for illuminating ananterior ocular segment.

The dichroic mirror 16 has a characteristic of allowing light with awavelength of light emitted from the external eye-illuminating lightsources 20 a and 20 b to pass through and reflecting light, except part,with a wavelength of light from an LED light source 21 for measurementand alignment, which will be described later.

The prism diaphragm 17 has three apertures, as shown in FIG. 2. Theupper and lower apertures have prisms 17 a and 17 b for polarizing lightflux to the right and left different from each other, respectively, andalso a filter having a spectral characteristic to absorb light with awavelength of light from the external eye-illuminating light sources 20a and 20 b and transmit light with a wavelength of light from the LEDlight source 21 for measurement and alignment.

On the other hand, the LED light source 21 for measurement and alignmentand a projection lens 22 are disposed on an optical axis L2 along thereflecting direction of the dichroic mirror 15, making up ameasuring-light projection system and an alignment-index projectionsystem. Furthermore, a dichroic mirror (not shown) having thecharacteristic of reflecting visible light and transmitting infraredlight is disposed at 45 degrees in a slanting position on the opticalaxis L2, and a fixing-light projection system for presenting a fixinglight for the subject eye E to be fixed is disposed on the optical axisalong the reflecting direction.

A lens 23, a pinhole plate 24, and a photo-detector 25 are placed on anoptical axis L3 along the reflection of the dichroic mirror 16. Theobjective lenses 10 and 11, the dichroic mirror 16, the lens 23, thepinhole plate 24, and the photo-detector 25 make up a cornealdeformation detection system for detecting a change in the amount ofcorneal reflection light.

A piston 28 which is pushed up by the driving of a solenoid 27 isslidably fitted in a cylinder 26 inside the fluid chamber 13. The nozzle12, the fluid chamber 13, the solenoid 27, and the piston 28 make up apressure section. The fluid chamber 13 has a pressure sensor 29 formonitoring the pressure in the fluid chamber 13.

The output from the image-pickup element 19 is connected to a controller31, to which an operating section 32, a monitor 33, the solenoid 27, andthe LED light source 21 are connected. Furthermore, the measuringsection accommodating the optical system of FIG. 1 is placed on a stage(not shown) and is driven by a motor in three axial directions, adirection along the optical axis L1 toward the subject eye E anddirections perpendicular to the axis L1.

When an operator pushes a measurement start switch of the operatingsection 32, illuminating light flux from the external eye-illuminatinglight sources 20 a and 20 b illuminates the anterior ocular segment ofthe subject eye E. The illuminating light flux reflected and diverged bythe anterior ocular segment is substantially collimated by the objectivelenses 10 and 11, passes through the observing window 14 and thedichroic mirrors 15 and 16, then passes through the aperture in thecenter of the prism diaphragm 17, and is imaged on the image-pickupelement 19 through the imaging lens 18.

The controller 31 performs rough alignment such that it senses a pupilto find the center of the pupil by binarizing the anterior ocularsegment image obtained from the image-pickup element 19 with anappropriate threshold, and when the relative position between theoptical axis L1 of the measuring section and the pupil of the subjecteye E in the plane in the direction of x, y perpendicular to the opticalaxis L1 is not in a permissible range, the stage is driven to move themeasuring section so as to be within the permissible range.

When the positioning of the subject eye E and the measuring section inthe plane perpendicular to the optical axis L1 has been substantiallyfinished, the controller 31 turns on the LED light source 21. The lightflux from the LED light source 21 is once imaged in the nozzle 12through the projection lens 22 and the dichroic mirror 15, reaches thesubject eye E, and is reflected by the cornea Ec. The light fluxreflected by the cornea EC is collected by the objective lenses 10 and11, passes through the observing window 14, and thereafter,substantially 50 percent passes through the dichroic mirror 15 and partof that 50 percent passes through the dichroic mirror 16.

The light flux that has passed through the dichroic mirror 16 is splitinto three pencils of light through the three apertures of the prismdiaphragm 17 and is imaged on the image-pickup element 19 through theimaging lens 18. At that time, the pencils of light that have passedthrough the upper and lower apertures of the prism diaphragm 17 arepolarized into and out of the plane of the paper by the polarizingprisms 17 a and 17 b, respectively, so that the positional relationshipamong the three-split bright point images of the cornea from the LEDlight source 21 varies depending on the relative position between thesubject eye E and the measuring section. The determination of thepositional relationship among the three-split corneal bright pointimages allows the positional relationship between the subject eye E andthe measuring section to be found.

For example, when the distance between the subject eye E and themeasuring section is longer than a predetermined distance, a cornealbright-point image into the plane of the paper on the image-pickupelement 19 is moved downward and an image on this side is moved upward.On the other hand, when the distance between the subject eye E and themeasuring section is shorter than the predetermined distance, thecorneal bright-point image into the plane of the paper on theimage-pickup element 19 is moved upward and the image on this side ismoved downward. When the positions of the subject eye E and themeasuring section in the plane perpendicular to the optical axis L1deviate from each other, the positional relationship between the subjecteye E and the measuring section can be found by sensing the gravity ofthe three corneal bright-point images or the position of the centralcorneal bright-point image.

The controller 31 performs close alignment such that it drives the stageso that the positional relationship between the subject eye E and themeasuring section is within a predetermined range. When the positioningbetween the subject eye E and the measuring section has been finished,the controller 31 drives the solenoid 27 to move the piston 28. Then thepressure in the fluid chamber 13 increases. The pressure is sensed bythe pressure sensor 29 and at the same time, a fluid-flow, for exampleairflow, having a strength with an increasing pressure within the fluidchamber 13 is blown from the nozzle 12 to the cornea Ec of the subjecteye E. The cornea Ec starts to be deformed depending on the strength ofthe fluid-flow.

In the corneal deformation detection system, when the curvature radius Rof the cornea has become a predetermined curvature radius Ra by thefluid-flow in pulse form, the photo-detector 25 detects a virtual imageformed by the reflection of the light flux by the cornea Ec, the lightflux being emitted from the LED light source 21 and projected on thecornea Ec, and light flux that has passed through pinholes in thepinhole plate 24. The pinhole plate 24 is arranged in the positionoptically conjugate with the objective lenses 10 and 11 and the lens 23.In the noncontact tonometer according to the first embodiment, theamount of light received by the photo-detector 25 increases as thecurvature radius R of the cornea Ec comes close to the predeterminedcurvature radius Ra, which becomes a peak value at which the curvatureradius Ra is infinite. In other words, the noncontact tonometer detectsa peak value when the cornea Ec becomes flat by the compressed air inpulse form.

Accordingly, by obtaining the value of an output signal from thepressure sensor 29 when an output signal from the photo-detector 25 inthe corneal deformation detection system has reached its peak value, apressure necessary to deform the curvature radius R of the cornea Ecinto Ra can be given, and so the intraocular pressure P of the subjecteye E can be given by converting the value.

FIG. 3 is a flowchart for the control operation of the first embodiment;in step 1, intraocular pressure measurement is performed by the roughalignment by the pupil-position sensing, the close alignment by thecorneal bright-point detection, the driving of the solenoid 27, and thecorneal deformation detection.

In step 2, it is determined by the controller 31 whether a predeterminednumber n of intraocular pressure measurements have been finished. Whenmeasured intraocular pressures include n values, from P1 to Pn, theprocess proceeds to step S3. When they are less than n, the processreturns to step S1, wherein the alignments and the intraocular pressuremeasurement are performed again.

FIG. 4 shows a setting screen displayed on the monitor 33. The firstembodiment can set two values in advance by the controller 31, as shownin FIG. 4. Referring to FIG. 4, “UPPER LIMIT: 20 mmHg ON” indicates anupper limit PH at which a series of measuring operations is changed whena measured intraocular pressure P has exceeded 20 mmHg. “LOWER LIMIT: 6mmHg OFF” indicates a lower limit PL at which a series of measuringoperations is changed when the measured intraocular pressure P hasfallen below 6 mmHg, wherein the indication is “OFF,” so that the lowerlimit PL is set invalid.

The set values of the upper limit PH and the lower limit PL can bearbitrarily varied, and also whether they are set valid or invalid canbe arbitrarily set.

In step S3, the controller 31 compares the respective n intraocularpressure values P1 through Pn measured n times with the upper limit PHto determine whether or not at least one intraocular pressure value Pexceeding the upper limit PH exists. When no intraocular pressure valueP exceeding the upper limit PH exists, the process proceeds to step S4.In the first embodiment, since the lower value PL is set to invalid, theprocess passes through the step S4 to step S5.

In step S5, it is determined whether or not the measurements of left andright intraocular pressures have been finished. When the measurement ofboth the left and right intraocular pressures has been completed, thecontroller 31 completes the measuring operation. When the measurement ofboth the left and right intraocular pressures has not been completed,the process proceeds to step S6, wherein the controller 31 drives thestage to move the measuring section to the other eye that has not yetbeen examined.

When the lateral movement has been accomplished, the process returns tostep S1, wherein the controller 31 performs intraocular-pressuremeasurement for the eye that has not yet been examined. The measurementis accomplished by the rough alignment by the pupil-position sensing,the close alignment by the corneal bright-point detection, the drivingof the solenoid 27, and the corneal deformation detection. Thereafter,the process proceeds to steps S2 through S5, wherein when theintraocular pressures of both eyes have been measured, the measuringoperation is completed.

On the other hand, in step S3, the controller 31 compares the respectiven intraocular pressure values P1 through Pn measured n times with theupper limit PH to determine whether or not at least one intraocularpressure value P exceeding the upper limit PH exists. When at least oneintraocular pressure value P exceeding the upper limit PH exists, theprocess of the controller 31 proceeds to step S7.

FIG. 5 is an explanatory diagram of the screen of the monitor 33 onwhich an intraocular pressure is displayed. The screen also displays amessage when the designated number n of measurements =2. When it hasbeen determined in step S3 that at least one intraocular pressure valueP exceeding the upper limit PH exists, the controller 31 displays nintraocular pressures P1 through Pn and a message M on the monitor 33 tonotify the operator that an intraocular pressure value P exceeding theupper limit PH exists and to recommend additional measurement forconfirmation, and then stops the continuous measuring operations. Thecontroller 31 then goes into an input standby mode for operationswitches of the operating section 32.

During the input standby mode, when the operator determines that anadditional intraocular-pressure measurement is necessary and pushes ameasurement start switch of the operating section 32, the process of thecontroller 31 proceeds to step S9. In step S9, the same control as thatin step S1 is performed, wherein intraocular pressure measurement isperformed by the rough alignment by the pupil-position sensing, theclose alignment by the corneal bright-point detection, the driving ofthe solenoid 27, and the corneal deformation detection.

When the additional intraocular-pressure measurement has been finished,the controller 31 again goes into the input standby mode for operationswitches of the operating section 32. On the other hand, when theoperator determines that the additional intraocular-pressure measurementis not necessary and pushes an R/L movement switch of the operatingsection 32, the process of the controller 31 proceeds to step S10.

In step S10, the controller 31 drives the stage to move the measuringsection laterally to the other eye position and comes into standby modefor inputting the operation switches of the operating section 32. Whenthe operator pushes the measurement start switch of the operatingsection 32, the process of the controller 31 returns to step S1, whereinthe series of measuring operations from step S1 through step S5 areperformed again.

With the noncontact tonometer for performing a designated number ofmeasurements by the series of measuring operations according to thefirst embodiment, as described above, the upper limit PH and the lowerlimit PL are set, the obtained intraocular pressure P is compared withthe upper limit PH or the lower limit PL, and when the obtainedintraocular pressure P is higher than the upper limit PH or lower thanthe lower limit PL, the series of measuring operations is stopped. Thetermination of measuring operations is indicated on a display devicesuch as the monitor 33 to notify the operator, thereby recommendingadditional measurement. Accordingly, there is no need to move themeasuring section into the measuring position again after completion ofthe measurements of both eyes. Thus, the efficiency of additionalmeasurement is increased and the operator is prevented from forgettingadditional measurement for confirmation.

According to the first embodiment, when it has been determined that theobtained intraocular pressure P is abnormal, the operator is notified ofthat by an indication on the display device such as the monitor 33;however, the operator can be notified by sound or a beeper, thusoffering similar effects.

Furthermore, according to the first embodiment, after the predeterminednumber n of intraocular-pressure measurements have been completed, themeasurements are compared with the upper limit PH or the lower limit PL.However, it is also possible to compare the intraocular pressure P withthe upper limit PH or the lower limit PL for each measurement, wherein,when the intraocular pressure P is abnormal, the series of measuringoperations is terminated and the message M is displayed on the monitor33 to notify the operator of it.

Second Embodiment

FIG. 6 is a flowchart for the control operation of a second embodiment.Steps S1 to S6 are the same as those of FIG. 3A. When the operatorpushes the measurement start switch of the operating section 32 of FIG.1, intraocular pressure is measured by the controller 31 in step S1 bythe rough alignment by the pupil position sensing, the close alignmentby the corneal bright point detection, the driving of the solenoid 27,and the corneal deformation detection. In step S2, it is determinedwhether or not the predetermined number n of intraocular-pressuremeasurements has been finished. When the number n ofintraocular-pressure measurements has been completed, the processproceeds to step S3, and when the number of times is less than n, theprocess returns to step S1, wherein the alignment and theintraocular-pressure measurement are performed again.

Two values of the upper limit PH and the lower limit PL can be set inadvance, as in the first embodiment. The upper limit PH and the lowerlimit PL can be arbitrarily varied and whether they are set valid orinvalid can be arbitrarily set.

Subsequently in step S3, the controller 31 compares the respective nintraocular pressure values, P1 through Pn measured n times with theupper limit PH to determine whether or not at least one intraocularpressure value P exceeding the upper limit PH exists. When nointraocular pressure value P exceeding the upper limit PH exists, theprocess proceeds to step S4. Also in the second embodiment, when thelower value PL is set to invalid, the process passes through the step S4to step S5.

In step S5, it is determined whether or not the measurements of the leftand right intraocular pressures have been accomplished. When themeasurements of left and right intraocular pressures have beencompleted, the controller 31 completes the measuring operation. When themeasurements of left and right intraocular pressures have not beenaccomplished, the process proceeds to step S6, wherein the controller 31drives the stage to move the measuring section to the other eye that hasnot been examined.

When the lateral movement has been completed, the process returns tostep S1, wherein the controller 31 performs intraocular-pressuremeasurement for the other subject eye that has not yet been examined, bythe rough alignment by the pupil-position sensing, the close alignmentby the corneal bright-point detection, the driving of the solenoid 27,and the corneal deformation detection. Thereafter, the process proceedsto steps S2 through S5, wherein when the intraocular pressures of botheyes have been measured, the measuring operation is completed.

In step S3, when it has been determined that at least one intraocularpressure value P exceeding the upper limit PH exists, the controller 31displays n intraocular pressures P1 through Pn on the monitor 33 andsounds a beeper to notify the operator that an intraocular pressurevalue P exceeding the upper limit PH exists at step S13, and the processproceeds to step S14.

In step S14, although the designated number n of measurements has beenfinished, a predetermined additional number m of intraocular-pressuremeasurements is automatically performed by the rough alignment by thepupil-position sensing, the close alignment by the corneal bright-pointdetection, the driving of the solenoid 27, and the corneal deformationdetection. When the automatic additional number m ofintraocular-pressure measurements has been finished, the processproceeds to step S5, and subsequently the series of measuring operationsis performed as described above.

With the noncontact tonometer for performing a designated number ofmeasurements by a series of measuring operations according to the secondembodiment, as described above, the upper limit PH and the lower limitPL are set, the obtained intraocular pressure P is compared with theupper limit PH or the lower limit PL, and when the obtained intraocularpressure P is higher than the upper limit PH or lower than the lowerlimit PL, the operator is notified by a beeper.

The predetermined number m of additional intraocular-pressuremeasurements is automatically performed and the measuring section ismoved to the eye position that has not yet been examined, where thepredetermined number n of intraocular-pressure measurements isperformed, thus increasing the efficiency of the additionalmeasurements. Also, there is no need for the operator to performadditional measurements for confirmation, thus preventing the problem ofthe operator's forgetting to perform additional measurements.

According to the second embodiment, it is also possible to set the upperlimit PH and the lower limit PL, and to compare the obtained intraocularpressure P with the upper limit PH or the lower limit PL. When theobtained intraocular pressure P is higher than the upper limit PH, thesolenoid 27 can be controlled to blow fluid with a force that isstronger than normal onto the cornea Ec, and when the intraocularpressure P is lower than the lower limit PL, the solenoid 27 can becontrolled to blow fluid with a weaker force onto the cornea Ec.

In this way, for the subject eye E having an intraocular pressure Phigher than the higher limit PH, the accuracy of measurement isimproved, and for the subject eye E having an intraocular pressure Plower than the lower limit PL, there is no need to blow fluid more thannecessary onto the subject eye E, thus reducing the load on the subject.

In the noncontact tonometer according to embodiments of the presentinvention, even when predetermined times of intraocular-pressuremeasurements are performed by a series of measuring operations, theupper limit and the lower limit are set, and an obtained intraocularpressure is compared with the upper limit or the lower limit, and whenthe obtained intraocular pressure is higher than the higher limit orlower than the lower limit, the series of measuring operations isstopped and that is displayed on a display device such as a monitor tonotify the operator, thus recommending additional measurement.Accordingly, there is no need to move a measuring section to themeasuring position again after the completion of the measurement of botheyes, thus increasing the efficiency of additional measurement. Also theoperator is prevented from forgetting to perform additional measurementsfor confirmation.

While the present invention has been described with reference to whatare presently considered to be the preferred embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments. On the contrary, the invention is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims. The scope of the following claims is to beaccorded the broadest interpretation so as to encompass all suchmodifications and equivalent structures and functions.

1. A noncontact tonometer comprising: fluid blowing means for blowingfluid onto a cornea to deform the cornea; measuring-light projectingmeans for projecting measuring light onto the cornea; cornealdeformation detecting means for detecting the measuring light reflectedby the cornea when the cornea is deformed by the fluid so as to have apredetermined curvature radius; calculating means for calculatingintraocular pressure on the basis of the detection by the cornealdeformation detecting means; control means for controlling measuringoperations of the noncontact tonometer performed sequentially apredetermined number of times; and comparing means for comparing theintraocular pressure obtained by the calculating means for each of thepredetermined times with a predetermined limit, wherein the controlmeans gives a warning if the intraocular pressure obtained by thecalculating means for at least one of the predetermined number of timesexceeds the predetermined limit.
 2. A noncontact tonometer according toclaim 1, wherein the control means adds a predetermined number ofmeasurements depending on the comparison by the comparing means.
 3. Anoncontact tonometer according to claim 1, wherein the control meanscomprises notifying means for notifying an operator of the comparison bythe comparing means.
 4. A noncontact tonometer according to claim 1,wherein the fluid blowing means comprises fluid control means forcontrolling the force of the fluid blown onto the cornea for varying theforce of the blown fluid depending on the comparison by the comparingmeans.
 5. A noncontact tonometer according to claim 1, wherein themeasuring operation utilizes pupil-position sensing means for alignment,corneal bright-point detection means for close alignment, a solenoid fordriving, and the corneal deformation detecting means.
 6. A noncontacttonometer according to claim 1, wherein the measuring operation utilizespupil-position sensing means for alignment, corneal bright-pointdetection means for close alignment, a solenoid for driving, the cornealdeformation detecting means, and notifying means for notifying theoperator of the comparison by the comparing means.
 7. A noncontacttonometer comprising: fluid blowing means for blowing fluid onto acornea to deform the cornea; measuring-light projecting means forprojecting measuring light onto the cornea; corneal deformationdetecting means for detecting the measuring light reflected by thecornea when the cornea is deformed by the fluid so as to have apredetermined curvature radius; calculating means for calculatingintraocular pressure on the basis of the detection by the cornealdeformation detecting means; control means for controlling measuringoperations of the noncontact tonometer so as to measure right and lefteyes sequentially a predetermined number of times, respectively; andcomparing means for comparing the intraocular pressure obtained by thecalculating means for each of the predetermined number of times with apredetermined limit, wherein the control means stops the measuringoperations after completion of the predetermined number of measurementsof the eyes under measurement if the intraocular pressure obtained bythe calculating means for at least one of the predetermined number ofmeasurements exceeds the predetermined limit.
 8. A noncontact tonometercomprising: a measuring unit adapted to measure an intraocular pressureof a first eye; and a control unit for controlling a movement of themeasuring unit to sequentially measure an intraocular pressure of asecond eye after measuring the intraocular pressure of the first eye;wherein the control unit terminates a measuring operation withoutcausing the measuring unit to move to measure the intraocular pressureof the second eye if the measured intraocular pressure of the first eyeexceeds a predetermined limit.
 9. The noncontact tonometer according toclaim 8, wherein the measuring unit includes; a fluid blowing unitadapted to blow fluid onto a cornea to deform the cornea; ameasuring-light projecting unit adapted to project measuring light ontothe cornea; and a corneal deformation detecting unit adapted to detectthe measuring light reflected by the cornea deformed by the fluid. 10.The noncontact tonometer according to claim 8, wherein the control unitcontrols a display of a message if the measured intraocular pressure ofthe first eye exceeds the predetermined limit.
 11. The noncontacttonometer according to claim 8, wherein the control unit controls themeasuring unit to additionally measure an intraocular pressure inresponse to activation of a measurement start switch, if the measuredintraocular pressure of the first eye exceeds the predetermined limit.12. The noncontact tonometer according to claim 8, wherein the controlunit controls the movement of the measuring unit in response toactivation of a movement switch, if the measured intraocular pressure ofthe first eye exceeds the predetermined limit.